Valve for rock drills



April 29, 1930.

A. R. MACK VALVE FOR ROCK DRILLS Filed Sept. 28, 1928 INVENTOR. Alba ZRMv'c e11 HIS A TTORNEY Patented Apr. 29, 1930 uurrn' STATS ALBERT R. MACK, or EASTON, PENNSYLVANIA, AssIGNoE T rNGEEsoLL-EAnn oo PANY, 0E JERSEY crrY, NEW JERSEY, A oonronarron or NEW JERSEY VALVE FOR ROCK DRILLS This invention relates to rock drills, but more particularly to a current thrown distributing valve for fluid actuated rock drills of the hammer type.

The objects of the invention are to obtain a rapid distribution of pressure fluid to the ends of the cylinder and to assure against leakage of pressure fluid from the valve chamber into the cylinder in advance of the piston, thus enabling the piston to deliver a heavy blow against the working implement which it is adapted to actuate.

Other objects will be inlpart obvious and in part pointed out hereinafter.

In the drawings illustrating a practical application of the invention and in which similar reference characters refer to similar parts,

Figure l is a sectional elevation of a portion of a rock drill having the invention applied thereto, V

Figure 2 is a transverse view taken through Figure 1 on the line 2-2 looking in the direction indicated by the arrows, and

Figure 8 is a perspective view of the valve.

Referring more particularly to the drawings, A designates generally a rock drill and B a cylinder in which is formed a piston chamber 0. The cylinder B is provided with free exhaust ports D which are controlled by a piston E reciprocable in the piston chamber C. j 4

A closure is provided for the front end of the piston chamber G in the form of a front cylinder washer F having a bore G to slidably receive an extension H of the piston E. In the rearward end of the cylinder B is an enlarged bore J to receive, among other elements, a back cylinder washer K which forms a closure for the rearward end of the piston chamber C. r

The drill A is provided with a back head L which is disposed at the back end of the cylinder B and may be secured thereto in any suitable manner, as for lnstance, by the usual side rods (not shown). In the present instance the back head L serves as a housing for a throttle valve 0 disposed in a throttle valve chamber P in the back head. The throt- 50 tle valveO has a lever Q whereby it may be rotated and in this instance has a central chamber R Which'may be in constant communication with a source of pressure fluid supply. In the wall of the throttle valve O is a port S through which pressure fluid may flow from the chaml P into a Passage T I cylinder washer K and the back head L. The

Valve mechanism V comprises in this instance a valve chest W in the form of a plate having v a rectangular aperture to form a valve chamber X and on the rearward end of'the valve chest W is seated a plate Y to form a closure for therearwa-rd end of the valve chamber X and also to form a'seat for the back head i In the form of the construction shown the rearward surface Z of the back cylinder washer K serves as a valve seat and in the back cylinder washer K is formed an inlet passage 7) which leads from the valvechamber X-to the rearward end of the piston chamber C. Similarly a front inlet passage 0 is formed in the back cylinder washer K and in the 'cylinder B to convey pressure fluid from the valve chamber X to the front end of the piston chamber C. The valve chamber X is constantly exposed at both ends to pressure fluid and such pressure fluid is conveyed thereto through supply ports (Z and e in the plate Y. The supply ports (Z and e are preferably located so that they open into the valvechamber X at or near its ends.

The distribution of pressure fluid from the valve chamber X to the ends of the piston chamber C is efiected by a distributing valve f slidable in the valve chamber X. Thedislar conformation and in this instance com prises a dome g, the upper surface it of which tributing valve f is preferably of rectanguis adapted to cooperate slidably with the plate Y Y for preventing leakage of pressure fluid =lateral flanges and p and said flanges are adaptedto slide on the surface Z of the back cylinder washer K and over the inlet passages b and c for controlling the admission of pressure fluid into the piston chamber. In the present instance the ends 9 and r of the flanges o and 79 respectively also serve as actuating surfaces against which pressure 7 fluid'may' act for throwing the valve.

- fluid into the ends of the piston chamber C By providing the valve 7 with the lat-' eral flanges 0 and p, pressure surfaces 8 and tare formed on the rearward ends or sides of the flange against wh ch pressure fluid mayc'onstantly act tending to press the valve firmly on the surface Z. This is desirable since it insures against leakage of pressure and thus prevents jshort stroking or thedelivering 'of'aweak blow of the piston E due to the presence of pressure fluid leaking to the end of the piston chamber C. towards which the piston E is travelling.

In order to maintain the weight of the valve 7 to a minimum said valve is provided with a transverse groove or recess a which,

may extend from one side of the valve to the other; In the present instance thisrece'ss is utilized as a means forstopping the valve in its limiting positions so that the actuating surfaces 9 and 7' will be held free of contact from the ends of the valve chamber. Ac-

. 'cordingly a pin 1; is seated in the back cylin- The operation of the device is as follows:

I With the throttle valve 0 in the open posi- 'tion, pressure fluid will flow from the'chamber B" through the passages T into the supply reservoir U. From thence the pressure 4 uid will flow through the supply ports (Z and a into the ends of the valve chamber X. With the valve 7 in the position illustrated in the drawings, the front inlet passage 0 will be covered by the flange 0 and the inlet passage 6 will be uncovered so' that pressure fluid will flow from the valve chamber X through the inlet passage 7) into the rearward end of the piston'chamber C toactuate the piston E forwardly in the direction of the working implement.

v As the piston E advances in a forwardly direction, the exhaust port or ports D will i be, uncovered thereby to permit the escape there will be a substantial drop in the pressure fluid acting against the surfaces in and 1" of the valve. The pressure fluid acting against the surfaces j and g on the opposite side of the valve 7 being equal to line pres sure will therefore be of sufiicient valueto overcome the reduced pressure acting against the surfaces k and 1. The valve 1 will then be thrown to its other extreme positionand the inlet passage 6 will then be covered by the flange p and the inlet passage 0 will be uncovered by the flange 0. 1

In the new position of the valve, pressure fluid will'flowthrough the inlet passage 0 into the piston chamber 0 and will impel the piston rearw ardly. "As the piston E approaches the rearward end of the "piston chamberQthe exhaust ports l) willbe uncovered and consequently, there will be decided drop in the pressure fluid existing in that end of the valvechamber X through which pressure fluid haspassedi'nto the cylinder. The valve f will then again be in state of unbalance and the pressure fluid acting, against the surfaces 70 and a will return the valve to its initial position.

From the foregoing description, it. will readily be seen that'the pressure fluid acting on the surfaces 8 and 't'of the flanges 0 and 32 will at all times tend to press the valve f firmly against the surface Z of the back cylinder washer K ln any of the positions which the valve may assume 1n the valve chamber.

In this way the inlet passages b and omay be properly closed and there will therefore :be

no leakage of pressure fluid nan the valve f chamber into the ends of the piston chamber towards which the I claim: V 1. In a fluid actuated rock drilhthe combination of a cylinder and a piston, 'afree piston E is moving.

inlet passages.

actuating the valve and for supplying the 2. Ina fluid actuated rock drill, the com bi'n'ation of a cylinder and a piston, a 'free exhaust port in the cylinder controlled by the piston, aval-ve chest having rectangular valve chamber, inletpassages leading from the valve chamber to the cylinderya pressure actuated distributing valve in the vlave chamber having flanges slidable over the in.-

let passages for controlling the admission of pressure fluid into the cylinder, said flanges being constantly exposed to pressure fluid onone side for holding the valveseated exhaust porti'n the cylinder controlled by the in the valve chamber, and supply ports in the valve chest to convey pressure fluid into the ends of the valve chamber for actuating the valve and for supplying theinlet passages.

3. In a fluid actuated rock drill, the combination of a cylinder and a piston, a free exhaust port in the cylinder controlled by the piston, a valve chest having a rectangular valve chamber, inlet passages leading from the valve chamber to the cylinder, a rectangular valve slidable in the valve chamber having actuating and holding surfaces at its ends constantly exposed to pressure fluid, lateral flanges on the valve slidable over'the inlet passages to control the admission of pressure fluid into the cylinder, and pressure surfaces on the top of the flanges constantly exposed to pressure fluid for holding the valve firmly seated in the valve chamber.

4. In a fluid actuated rock drill, the combination of a cylinder and a piston, a free exhaust port in the cylinder controlled by the piston, a valve chest having a rectangular valve chamber, inlet passages leading from the valve chamber to the cylinder, a rectangular valve slidable in the valve chamber having actuating and holding surfaces at its ends constantly exposed to pressure fluid, lateral flanges on the valve slidable over the inlet passages to control the admission of pressure fluid into the cylinder, pressure surfaces on the top of the flanges constantly exposed to pressure fluid for holding the valve firmly seated in the valve chamber, a recess in the valve, and a pin in the valve chest ex tending into the recess to act as a stop for the valve. I

In testimony whereof I have signed this specification.

I ALBERT R. MACK. 

